Fungal glutaminases: Production, optimization, and purification with antimicrobial activities of L- glutaminase from novel isolate Aspergillus tamarii AUMC 10198 under solid-state fermentation

Abstract

Introduction Fungal L-glutaminase has garnered significant attention in recent times with respect to its possible applications in the field of medical therapy and biotechnology. The principal aim of this research was to pick out microbial strains that can efficiently produce L-glutaminase from agricultural by-products under solid-state fermentation (SSF). Various fungal isolates were screened for extracellular L-glutaminase production. During the fermentation process, numerous parameters were adjusted one variable at a time (OVAT) to increase L-glutaminase production. The L-glutaminase of Aspergillus tamarii AUMC 10198 was purified in three sequential stages. The properties of the purified enzyme and the antimicrobial efficiency were also fulfilled. Results The potentiality of four out of fourteen fungal isolates served as indicators of the enzyme's productivity. The fungus Aspergillus tamarii AUMC 10198, designated with the GenBank accession number OQ976977, was determined to be the potent for estimating L-glutaminase synthesis, under SSF using wheat bran as a solid substrate. The solid-state yield of L-glutaminase exhibited a 3.20-fold increase in comparison to the unoptimized state. The Aspergillus tamarii AUMC 10198 L-glutaminase underwent three stages of purification, resulting in an increase in enzyme productivity by 12.90 times. Following these steps, the ultimate enzyme recovery was 18.45%. The isolated L-glutaminase exhibited optimal activity at a pH of 8, a temperature of 45 °C, and partial stability up to 60 °C, as determined by characterization. The purified L-glutaminase exhibited a Vmax of 10.10 U/ml and a Km of 0.28 mg/ml when glutamine was used as the substrate. The metal ions Fe2+, Ca2+, K+, Mg2+, and Na+ demonstrated significant enzyme-activating properties at a concentration of 0.01 M, resulting in an enhancement of L-glutaminase productivity. The antimicrobial activity indicates its capability for various therapeutic and pharmaceutical applications. Conclusion The present investigation revealed that the local fungal strain of Aspergillus tamarii AUMC10198 could potentially be utilized in the production of L-glutaminase for industrial applications from agricultural by-products.